Apparatus and method for driving a lamp unit, and liquid crystal display device using the same

Abstract

An apparatus for driving a lamp comprising at least one lamp, an inverter to supply an alternating current signal, a transformer to boost the signal from the inverter and to supply the boosted signal to the lamp, and a safety circuit to detect the signal flowing to the lamp and to compare the signal with a predetermined threshold to shut down the inverter in accordance with the compared result.

1. An apparatus for driving a lamp unit, comprising:
 at least one lamp; 
 an inverter to supply an alternating current signal; 
 a transformer to boost the signal from the inverter and to supply the boosted signal to the lamp, wherein the transformer includes
 a primary winding wire connected to the inverter to generate the alternating current signal, 
 a secondary winding wire induced by the primary winding wire to amplify the alternating current signal, and 
 an auxiliary winding wire arranged between the primary winding wire and the secondary winding wire; and 
 
 a safety circuit to detect the boosted signal flowing to the lamp and to compare the detected signal with a predetermined threshold to shut down the inverter based on the comparison, wherein the safety circuit includes
 a detector to detect the boosted signal, 
 a rectifier to rectify the detected signal from the detector into a direct current level, 
 a comparing part to compare the rectified signal from the rectifier with the predetermined threshold, and 
 a switching part to switch the apparatus between a shut down state and an operating state in response to the resulting signal from the comparing part, 
 
 wherein the detector is connected between the secondary winding wire and the lamp to detect the amplified signal and the detected signal is a current. 
 
     
     
       2. The apparatus according to  claim 1 , wherein the rectifier includes:
 a half-wave rectifier having diodes coupled in parallel with each other and connected to the detector; and 
 an integrating circuit to integrate a signal from the half-wave rectifier to supply the integrated signal to the comparing part. 
 
     
     
       3. The apparatus according to  claim 1 , wherein the switching part includes a transistor having:
 a base terminal connected to an output terminal of the comparing part; 
 a collector terminal connected to the inverter; and 
 an emitter terminal connected to ground. 
 
     
     
       4. A method for driving at least one lamp connected to an inverter to supply an alternating signal and a transformer to boost the signal from the inverter and to supply the boosted signal to the lamp, comprising:
 detecting a signal flowing to the lamp; 
 comparing the detected signal flowing to the lamp with a predetermined threshold, wherein the detected signal is a current; and 
 shutting down the inverter based on the comparison, 
 wherein the transformer includes a primary winding wire connected to the inverter to generate the alternating current signal, a secondary winding wire induced by the primary winding wire to amply the alternating current signal, and an auxiliary winding wire arranged between the primary winding wire and the secondary winding wire. 
 
     
     
       5. The method according to  claim 4 , further comprising rectifying the detected signal into a direct current level, wherein the comparing step includes comparing the rectified signal with the predetermined threshold, and the shutting down step includes switching the inverter between one of a shut down state and an operating state in response to the comparing step. 
     
     
       6. The apparatus according to  claim 5 , wherein the rectifying step includes:
 passing the detected signal through a half-wave rectifier having diodes coupled in parallel with each other; and 
 integrating the half-wave rectified signal to compare with the predetermined threshold. 
 
     
     
       7. A liquid crystal display device, comprising:
 a liquid crystal display panel to display an image; 
 at least one lamp to irradiate light to the liquid crystal display panel; 
 an inverter to supply an alternating current signal; 
 a transformer to boost the signal from the inverter and to supply the boosted signal to the lamp, wherein the transformer includes
 a primary winding wire connected to the inverter to generate the alternating current signal, 
 a secondary winding wire induced by the primary winding wire to amplify the alternating current signal, and 
 an auxiliary winding wire arranged between the primary winding wire and the secondary winding wire; and 
 
 a safety circuit to detect the boosted signal flowing to the lamp and to compare the detected signal with a predetermined threshold to shut down the inverter based on the comparison, wherein the safety circuit includes
 a detector to detect the boosted signal, 
 a rectifier to rectify the detected signal from the detector into a direct current level, 
 a comparing part to compare the rectified signal from the rectifier to the predetermined threshold, and 
 a switching part to switch the apparatus between a shut down state and an operating state in response to the resulting signal from the comparing part, 
 
 wherein the detector is connected between the secondary winding wire and the lamp to detect the amplified signal. 
 
     
     
       8. The liquid crystal display device according to  claim 7 , wherein the rectifier includes:
 a half-wave rectifier having diodes coupled in parallel with each other and connected to the detector; and 
 an integrating circuit to integrate a signal from the half-wave rectifier to supply the integrated signal to the comparing part. 
 
     
     
       9. The liquid crystal display device according to  claim 7 , wherein the switching part includes a transistor having:
 a base terminal connected to an output terminal of the comparing part; 
 a collector terminal connected to the inverter; and 
 an emitter terminal connected to ground. 
 
     
     
       10. An apparatus for driving a lamp unit, comprising:
 at least one lamp; 
 an inverter to supply an alternating current signal; 
 a transformer to boost the signal from the inverter and to supply the boosted signal to the lamp, wherein the transformer includes
 a primary winding wire connected to the inverter to generate the alternating current signal, 
 a secondary winding wire induced by the primary winding wire to amplify the alternating current signal, and 
 an auxiliary winding wire arranged between the primary winding wire and the secondary winding wire; and 
 
 a safety circuit to detect the boosted signal flowing to the lamp and to compare the detected signal with a predetermined threshold to shut down the inverter based on the comparison, wherein the detected signal is a voltage, the safety circuit including
 a detector to detect the boosted signal, wherein the detector is connected between the secondary winding wire and the lamp to detect the amplified signal, 
 a rectifier to rectify the detected signal from the detector into a direct current level, 
 a comparing part to compare the rectified signal from the rectifier to the predetermined threshold, and 
 a switching part to switch the apparatus between a shut down state and an operating state in response to the resulting signal from the comparing part, the switching part including a transistor having a base terminal connected to an output terminal of the comparing part, a collector terminal connected to the inverter, and an emitter terminal connected to ground. 
 
 
     
     
       11. The apparatus according to  claim 10 , wherein the rectifier includes:
 a half-wave rectifier having diodes coupled in parallel with each other and connected to the detector; and 
 an integrating circuit to integrate a signal from the half-wave rectifier to supply the integrated signal to the comparing part.